Compressor protective device



Aug. 25, 1936.

P. L. CRITTENDN E-r COMPRESSOR PROTECTIVE DEVICE Filed June 15, 19:55

Patented Aug. 25, 1936 UNITED STATES PATENT OFFICE coMrnEssoa PROTECTIVE nevica Application June 15, 1935, Serial No. 26,824

13 Claims.

This invention relates to a compressor protective means and more particularly to a safety or protective means responsive to temperature conditions of the fluid compressed by the compressor and controlling means for unloading the compressor. y

In the operation of uid compressors, such as air compressors, thereis a possibility that the temperature of the iiuid compressed will increase beyond a safe limit, and if this occurs, it may cause an explosion, a fire or result in damage to the compressor.

As usually constructed multi-cylinder compressors have unloading means associated with each of the cylinders, together with common means for controlling the operation of the unloading means for all of the cylinders.

It is the principal object of this invention to provide a multi-cylinder compressor in which each cylinder has fluid pressure operated unloading means associated therewith, Itogether with means responsive to temperature conditions oi!v the uid compressed in each of these cylinders for controlling the operation of the unloading means associated with said cylinder.

Another object of the invention is to provide a compressor having unloading means associated therewith, the unloading means being operable in response to `an unloading controller which is operable in accordance with operating conditions of the compressor, or to means responsive to temperature conditions of the fluid compressed by the compressor.

A further object of the invention is to. provide a multi-cylinder compressor in which each cylinder has fluid pressure operated unloading means associated therewith, together with means responsive to temperature conditions of the fluid compressed in the cylinder for controlling the l operation of the unloading means associated with said cylinder, and having common means for controlling the operation oi! the unloading means for all of the cylinders.

Another object of the invention is to provide a multi-cylinder compressor having means for effecting the unloading of all of the cylinders, together with means associated with each of the cylinders to eil'ect unloading of the individual cylinders in response to temperature conditions of the iiuid compressed in each of said cylinders.

A further object of the invention is to provide a compressor having means to effect unloading thereof in response to temperatureconditions of -the iiuid compressed by the compressor together` with a signal operable when the compressor is unloaded by the means'responsive to temperature conditions ci the iluid compressed therein.

Another object of the invention is to provide a compressor having means responsive to temperature conditions in the discharge passage 5 leading from the compressorLsaid means being positioned so as to be protected from oil and foreign matter discharged with the air compressed by the compressor.

Other objects of the invention and features 10 of novelty will be apparent from the following description taken in connection with the accompanying drawing, in which Fig. 1 is a. diagrammatic view of a compressor incorporating the protective means provided by this invention, and 15 Fig. 2 is an enlarged sectional view taken substantially along the line 2-2 of Fig. 1.

Referring to the drawing, the safety means provided by this `invention is shown diagrammatically in connection with a multi-cylinder 20 compressor. As shown, each of the cylinders i has a bore therein in which is located a piston 2, and to which is detachably secured by suitable means, not shown, a. cylinder head 3.

The cylinder head 3 has a chamber 5 formed 25 therein, in which is located the exhaust valve 6, and in addition has a chamber l8 formed therein, with which is associated the inlet valve 9.

The exhaust valve 0 is adapted to engage a seat I0 formed around a passage communicating 30 with the chamber 5 and with the chamber in the cylinder I above the piston 2, and has a hollow stem II formed integral therewith which is slidable in and is guided by the tubular extension I2, which is formed integral with the 35 closure member I5 whichv is secured on the top oi.' the cylinder head 3 and closes the. chamber 5.

A spring I8 is interposed between the closure member lI5 and the exhaust valve 6 and normally urges the valve B into engagement with the 40 seat I 0.

The chamber 5 is connected with the reservoir 20 by way of the branched pipe 2l, the other branches of which are connected to the other cylinders of the compressor as shown in Fig. 1 45 of the drawing.

. The chamber within the tubular member i 2 communicates with the chamber 5 by way of openings extending through the walls of the tubular member I2.v

A bushing 30 is secured in the closure member I5 and has a tapered end portion which extends into the chamber within the tubular portion I2. The bushing 30 has an aperture 3l extending therethrough, the lower end of which is conical 55 in form, the portion-of larger diameter being located at the, bottom. A plug 32, formed of a suitable fusible metal adapted to melt when increased to a predetermined temperature is positioned in the conical portion of the aperture 3i.

The inlet valve 9 has a tubular extension 55 formed integral therewith and extending through abore in the cylinder head 3 and has a spring seat 36 secured on the upper end thereof by means of a pin Il. A spring 38 is interposed between the spring seat 96 and a portion of the cylinder head 3 and normally urges the inlet valve 9 into engagement with a. seat 40 formed on the cylinder head 3.

The compressor has unloading means associated with the inlet valve, and as shown comprises a closure member 42 secured on the cylinder head 3 over the inlet valve 9. This member has a bore 44 formed therein in which is mounted a. piston 46 having a stem 41 formed integral therewith and engageable with the tubular extension 35 on the inlet valve 9.

The upper end of the bore 44 is closed by a member 50 and the piston 46 is normally urged into engagement with this member by means of a spring 52.

The member 50 has a double seating check valve incorporated therein. As shown in the drawing the member 50 has a bore or passage 55 formed therein and communicating intermediate its ends by way of the passage 58 with the chamber above the piston 46. A ball check valve 59 is positioned in the bore 55 and is engageable with the seat 50 formed at one end of the bore 55 and the seat 6| formed at the other end of the bore 55.

One end of the passage 55 is connected by way of a pipe 65 and an elbow 66 with the aperture 3l in the bushing 30 above the plug 32. 'I'he elbow 66 has an atmospheric exhaust passage 68 therein communicating with the passage in the elbow and with the atmosphere.

The other end of the passage 55 is connected by means of a branched pipe 69 with an unloading device, indicated generally by the reference numeral 10, and which may be of any suitable well known construction, and which operates to control the supply and release of fluid under pressure to and from the pipe 69 in response to the variations in the pressure of the fluid compressed by the compressor or to other operating conditions, such as the speed of the compressor or` the operation of the compressor lubricating system. One form of unloading controller which we may employ is shown in the copending application of. Burton S. Aikman, Serial No. 4,042, filed January 30, 1935.

In the operation of the compressor on the downward stroke of the piston fluid is drawn into the chamber above the piston 2 through the chamber 8 and past the inlet valve 9. On the upward stroke of the piston the inlet valve 9 seats and the fluid which is compressed unseats the exhaust valve 6 so that the fluid flows to the chamber 5 and therefrom by way of the pipe 2| to the reservoir 20.

When the pressure of the uid in the reservoir 20 is built up to a. predetermined value or upon the occurrence of other conditions to which the unloading means is responsive, the unloading device 10 operates to supply fluid under pressure from the reservoir by way of the branched pipe 69 to the passage 55, where the fluid forces the ball check valve 59 away from the seat 6I and into engagement with the seat 50. Fluid thereupon flows from the passage 55 by way of the passage 56 to the chamber above the piston 46 and forces this piston downwardly against the spring 52 so that the stem 41 engages the end of the tubular portion 55 associated with the inlet valve 6, with the result that the inlet valve 9 is moved away from the seat 46 and the compressor is unloaded.

The ball check valve 59 operates at this time to prevent fluid from flowing from the passage 55 to the pipe 65 and therefrom to the aperture 3| where it might operate to displace the fusible plug 32. The compressor remains unloaded until the unloading device 10 operates to /eil'ect loading thereof by releasing fluid under pressure from the pipe 69, which permits the spring 52 to move the piston 46 upwardly and thus permit the inlet valve 9 to again be moved to its seat by the spring 38.

If for any reason, such as for instance, a

'leaking exhaust valve 6 which permits fluid to flow from the reservoir 20 back into the chamber above the piston 2, therebyv increasing pressure of uld in this chamber and causing a corresponding increase in`the temperature of the fluid compressed by the compressor, the temperature of the fluid compressed should exceed a predetermined value, the temperature of the fusible plug 32 will be increased, and if the increase in the temperature of this plug is sufflcient the plug will be melted and fluid will be permitted to flow from the chamber 5 through the aperture 3i to the pipe 65.

The fluid which is supplied to the pipe 65 forces the ball check valve 59 away from the seat 60 and into engagement with the seat 6| so as to cut off communication between the unloading means and the unloading controller 16 and the passage leading to the unloading means associated with the other cylinders of the compressor. The fluid which is supplied to the passage 55 flows through the passage 58 to the chamber above the piston 46, forcing thel piston downwardly and moving the inlet valve 9 away from the seat 40. It will be seen, therefore, that on an increase in the temperature of the fluid compressed in a cylinder to a value above a predetermined value the cylinder will be unloaded.

It will be seen also that the unloading means is arranged so that the unloading means for each cylinder is separate andindividual to itself and the unloading of any cylinder as a result of temperature conditions in this cylinder does not affect the other cylinders of the compressor, the unloading means for each cylinder being cut oi yfrom the unloading controller when fiuid under pressure is supplied thereto as a result of the operation of the temperature responsive means. The other cylinders of the compressor, therefore, will continue to operate in the normal manner after a cylinder has been unloaded because of temperature conditions of the fluid compressed in this cylinder.

When fluid is supplied to the unloading means as a result of melting of the fusible plug 32, fluid under pressure is permitted to escape to the atmosphere by Way of the passage 68 and this produces an audible signal to indicate to the operator that a cylinder is unloaded.

It will be seen also that the fusible plug 32 is located in the chamber within the tubular member I2 and is shielded from the fluid in the chamber 5, although it is in communication therewith. As the fusible plug is shielded from the flow of uid through the chamber 5 it will not become of fluid under pressure to the unloading means ascovered with carbon or oil deposited in the chamber 5 as a result of the flow of fluid therethrough and hence will at all times be immediately responsive to an increase in the temperature of the iluid in the chamber 5.

While one embodiment of the compressor protective device provided by this invention has been illustrated and described in detail it should be understood that the invention is not limited to these details of construction and that numerous changes and modifications may be made without departing from the scope of the following claims.

Having now described our invention, what we claim as new and desire to secureby Letters Patent, is:

l. In a fluid compressor, a plurality of cylinders in which fluid is compressed, each of said cyl-` inders having unloading means associated therewith, common means to control the operation of the unloading means for all of the cylinders, each of said cylinders having means associated therewith and responsive to temperature conditions of the fluid compressed in said cylinder and operable to effect the operation of the unloading means associated with said cylinder.

2. In a fluid compressor, -a plurality of cylinders in which fluid is compressed, each of said cylinders having unloading means associated therewith, common meansto control the operation of the unloading means for all of the cylinders, each of said cylinders having means associated therewith and responsive to temperature conditions of the fluid compressed in said cylinder and operable to eiect the operation of the unloading means associated with said cylinder independently of the common means controlling the operation of the unloading means for all of the cylinders;

3. In a fluid compressor, a plurality of cylinders in which fluid is compressed, each of said cylinders having fluid pressure operated unloading means associated therewith, common means for controlling the supply of fluid to all of said unloading means, each of said cylinders having means associated therewith and responsive to temperature conditions of the fluid compressed in the cylinder and operable to control the supply of fluid under pressure to the unloading means associated with said cylinder.

4. In a fluid compressor, a plurality of cylinders in which fluid is compressed, each of said cylinders having fluid pressure operated unloading means associated therewith, common means for controlling the supplyof fluid to all of said unloading means, each of said cylinders having means associated therewith and responsive to temperature conditions of the fluid compressed in the cylinder and operable to control the' supply of fluid under pressure to the unloading means associated with said cylinder, each of said cylinders having means associated therewith and operable responsive to the supply of fluid to the unloadinggmeans by the temperature responsive means to close the communication through which fluid is supplied to the unloading means by the common means.

5. In a fluid compressor, a plurality of cylinders in which fluid is compressed, each of said cylinders having fluid pressure operated unloading means associated therewith, common means for controlling the supply of fluid to all of said unloading means, each of said cylinders having means associated therewith and responsive to temperature conditions of the fluid compressed in the cylinder and operable to control the supply sociated with said cylinder, each of said cylinders having means associated therewith and operable responsive to the supply of fluid to the unloading means by the common means to close the communication through which fluid is supplied to the unloading means by the temperature responsive means.

6. In a fluid compressor, a plurality of cylinders in which fluid is compressed, each of said cylinders having fluid pressure operated unloading means associated therewith, common means for controlling the supply of fluid to all of said unloading means, each of said cylinders having means associated therewith and responsive to temperature conditions of the fluid compressed in the cylinder and operable to control the supply of fluid under pressure to the unloading means associated with said cylinder, and a signal operable in response to the supply of fluid to the unloading means by the temperature responsive means.

7. In a lluid compressor, a plurality of cylin-v the unloading means associated with said cyl.

inder, and a signal operable in response to operation of the temperature responsive means to effect operation of the unloading means.

8. In a fluid compressor, a plurality of cylinders in which fluid is compressed, each of said cylinders having fluid pressure operated unloading means associated therewith, each of said cylinders having means associated therewith and responsive to temperature conditions of the fluid compressed therein and controlling a passage through which fluid may be supplied to the unloading meansassociated with said cylinder, an unloading controller controlling passages through which fluid may be supplied to the unloading means associated with all of said cylinders, each of said cylinders having means associated therewith and operable responsive to the supply of fluid to the unloading` means through the passage controlled by the temperature responsive means or through the passage controlled by the unloading controller to cut off communication between the unloading means and thek other of said passages.

9. In a `fluid compressor, a cylinder in which fluid is compressed, fluid pressure operated unloading means associated with said cylinder, said cylinder having associated therewith means responsive to temperature conditions ,of the fluid compressed therein and controlling a passage through which fluid under pressure may be supplied to the unloading means, an unloading controller controlling a passage through which fluid may be supplied to the unloading means, and means responsive to the supply of uid to the unloading means through eitherof said passages for cutting off communication between the unloading means and the other of said passages.

10. In a fluid compressor, a cylinder in which fluid is compressed, fluid pressure operated unloading means assoclated with said cylinder, said cylinder having associated therewith means replied to the unloading means, an unloading controller controlling a passage through which uid may be supplied to the unloading means,means responsive tothe supply of fluid to the unloading means through either of said passages for cutting oi! communication between the unloading means and the other of said passages, and a signal operable in response to the supply oi' iluid to the unloading means through the passage coni trolled by the temperature responsive means.

11. In a iluid compressor, a cylinder in which iluid is compressed, iluid pressure operated unloading means associated with said cylinder, means operated inl response to operating conditions of the compressor for supplying iluid under pressure to said unloading means to eilect unloading of the compressor, and means responsive to the temperature conditions of the fluid compressed by the compressor for also supplying iluid under pressure to said unloading means.

12. In a iluid compressor, a cylinder in which iiuid is compressed, fluid pressure operated unloading means associated with said cylinder, means operated in response to operating conditions of the compressor for supplying fluid under 2,052,101; "through which fluid under pressure may be suppressure to said unloading means to effect un` loading of the compressor, means responsive tov the temperature conditions yof the fluid compressed by t'he compressor for also supplying fluid under pressure to said unloading means, and a check valve operated by the ilow of iluid under pressure from one of said iluid pressure -supply means for cutting of! communication from said unloading means to the other iluid pressure' under pressure to said unloading means,'and a 20 signal operable in response to operation of the temperature responsiveI means to supply iluid under pressure to the unloading means,

PHILIP L. C'RI'ITENDEN. 25

.' BURTON S. AIKMAN. 

